API Development and System Integration Services

Most organizations do not need another system. They need the ones they have to talk to each other: the ERP to the store, the CRM to billing, the EHR to the patient app, the HR platform to the identity directory. PS3G’s API development services and system integration services build those connections: REST and GraphQL APIs, point-to-point integrations, middleware on an integration platform, event-driven pipelines and scheduled data syncs. The work is scoped to the problem, whether you are a founder exposing your first public API, an operations team tired of re-keying orders, or an IT department with forty systems and no map of how they connect.

Connect what you have before you buy more

Re-keying, CSV exports and the spreadsheet that reconciles two systems are integration debt. They cost staff time every day, produce errors that surface weeks later and make every new system harder to add. Before recommending new software, we ask what the existing systems could do if they were connected properly, because that is usually the faster fix.

Integration also protects what you have already paid for. An API in front of an older system lets you build a new portal, a mobile app or an AI assistant on top of it without replacing it.

What our API development services include

APIs

REST APIs with an OpenAPI specification, GraphQL where clients need flexible queries, authentication and rate limiting, generated SDKs and documentation a partner can use without a call. Published through Azure API Management, AWS API Gateway or Kong when you need analytics, keys and throttling in one place.

Integrations

Point-to-point connections between two systems when that is all you need, built with error handling, retries and logging rather than a script that fails silently. Each one has a documented contract: which system owns each field, how often data moves and what happens on failure.

Middleware and iPaaS

When several systems exchange data, a middleware layer keeps the connections manageable. We work with Azure Logic Apps and Power Automate, MuleSoft, Boomi and Workato, and with lighter tools such as Zapier or Make for low-volume workflows, choosing by volume, complexity and what your team can maintain.

Event-driven pipelines

Webhooks, queues and event buses (Azure Service Bus and Event Grid, AWS SQS, SNS and EventBridge, Kafka) for systems that must react in near real time: an order placed, a patient checked in, a payment received. Designed so duplicate or failed events cannot corrupt data.

Data syncs

Scheduled and change-data-capture pipelines with Azure Data Factory, SSIS, Informatica or DataStage that keep reporting databases and warehouses current. Larger analytics pipelines belong to our big data and data engineering practice.

Common integrations

System type	Examples	Typical work
ERP	SAP, Dynamics 365 Business Central and Finance, Oracle, NetSuite, QuickBooks	Orders, invoices, customers and stock synchronized with the store, CRM or portal; see our ERP solutions
CRM	Salesforce, HubSpot, Dynamics 365 Sales	Lead capture from web forms, account and contact sync, activity and support history in one view
EHR and healthcare	HL7 v2 interfaces, FHIR APIs, lab, pharmacy and telehealth systems	EHR integration services for health-tech products, device data and patient apps, with our healthcare software development team
Payments	Stripe, Authorize.Net, PayPal	Checkout, subscriptions, webhooks for payment events, reconciliation to accounting
Ecommerce	Shopify, WooCommerce, marketplaces	Orders to the ERP and warehouse, inventory and pricing back to the store
HR and identity	Workday, ADP, BambooHR, Entra ID, Okta	Employee onboarding and offboarding, account provisioning with SCIM, directory sync for portals
Marketing and analytics	HubSpot, Mailchimp, Klaviyo, GA4	Customer events and segments pushed to marketing tools, conversions pushed back to analytics
AI systems	LLM-based assistants and agents	APIs that let an assistant read and act on systems of record safely, built with our AI development team

Security, versioning and monitoring

Security. OAuth 2.0 and OpenID Connect for user-facing APIs, API keys with rotation and scopes for system-to-system calls, TLS everywhere, input validation, rate limiting, secrets held in Azure Key Vault or AWS Secrets Manager, and audit logs for every call that reads or changes sensitive data. For healthcare integrations we design to the HIPAA Security Rule safeguards and check the current official text with you rather than quoting thresholds. This is general information, not legal advice.

Versioning. Every API carries a version in its URL or headers, breaking changes go in a new version with a published deprecation period, and contract tests catch accidental changes before they reach a partner. The OpenAPI document is the source of truth and is generated from the code, not maintained by hand.

Monitoring. Dashboards for call volume, latency and error rates, alerts when a connection fails or falls behind, dead-letter queues for failed events, safe retries, and reconciliation reports that compare the two sides of a sync. Every integration ships with a runbook that says what to check and who to call.

Our process

1. Inventory and map. The systems involved, their owners, the data that moves between them, volumes and the current manual steps. Deliverable: an integration map and a prioritized list.
2. Design. API contracts, field-level data mappings, ownership of each field, error handling and the sync pattern (real time, event or batch) for each connection.
3. Build. In sprints, against vendor sandboxes and mocks, with the contract tests written alongside the code.
4. Test. Contract, end-to-end and load tests, plus failure injection: the ERP is down, the token expires, a record is malformed.
5. Deploy and monitor. CI/CD, environment configuration, monitoring and alerting switched on before go-live, and a hypercare period.
6. Hand over. Documentation, runbooks and access transferred to your team, with a maintenance arrangement if you want one.

Send us your list of systems and we will come back with an integration map.

Engagement models and how we start

• Fixed-scope project. One API or a defined set of integrations with a fixed price and acceptance tests.
• Dedicated team or staff augmentation. Integration engineers working through a backlog with your team, month to month.
• Managed services. We run and monitor the integrations under defined SLAs, including vendor API changes.
• Advisory. An integration architecture review or an iPaaS-versus-custom platform selection.

How we start: a first conversation, a short assessment of the systems and data involved, and a written proposal with the integration map attached. APIs usually sit under a product or portal, which our web application development team can deliver in the same engagement.

Why PS3G

We build and run our HIPAA-compliant EHR and telehealth platform, DocVilla, so healthcare interfaces such as HL7 and FHIR and the discipline of keeping integrations running in production are part of our daily work. More than a decade of building software, a headquarters in Wilmington, Delaware with a delivery center in India for extended monitoring hours, Microsoft and open-source certified engineers and a testing center of excellence stand behind every integration.

Related services

• Web application development: the portals and products that sit on top of the APIs.
• ERP solutions: SAP and Dynamics implementations and the integrations around them.
• Healthcare software development: HIPAA-by-design products with HL7 and FHIR interfaces.
• AI development: assistants and agents that act on your systems through APIs.
• Big data and data engineering: pipelines that feed warehouses and analytics.

Browse all PS3G services.

Guides on this topic

• EHR Integration Explained: HL7 v2, FHIR and What Vendors Must Prepare

Frequently asked questions

What is the difference between API development and system integration?

API development builds the interface a system exposes so other software can use it: endpoints, authentication, documentation and versioning. System integration connects two or more systems so data and events flow between them, using their APIs, files, databases or middleware. Most projects involve both, for example building an API over an older system and then integrating a new portal and the CRM with it.

Do we need middleware or an iPaaS?

Not for one or two connections; a well-built point-to-point integration is simpler to run. Middleware earns its place when several systems exchange data, when the same transformation is needed in more than one place, or when business users need to adjust workflows without code. We recommend the lightest option that your team can maintain, and we say when a tool would add cost without adding control.

Can you integrate with our ERP, such as SAP or Dynamics 365?

Yes. ERP integration is the most common work we do: orders, invoices, customers, prices and stock moving between the ERP and a store, CRM or portal, with the ERP kept as the system of record. We use the vendor’s supported interfaces, build the field mappings with your finance and operations teams, and add monitoring and reconciliation so a failed sync is caught the same day.

How do you stop integrations from breaking when a vendor changes its API?

Contract tests run on a schedule against the vendor’s API and fail the moment a response changes shape. Versioned endpoints, deprecation tracking for the vendors you depend on, alerts on error rates and a runbook for each integration mean the change is handled as planned work rather than an outage. Under a managed-services plan we make those updates for you.

Do you provide EHR integration services?

Yes. We build HL7 v2 interfaces and FHIR API integrations between EHRs, labs, pharmacies, devices, telehealth tools and patient-facing apps, designed to HIPAA safeguards with audit logging and access controls. Because we run our own EHR platform, we understand both sides of the interface. Our guide to EHR integration explains what vendors must prepare before a connection goes live.

How is integration work priced?

As a fixed-scope quote per API or integration when the systems and data are known, or as a dedicated team when there is a backlog of connections to work through. The quote follows the inventory and mapping step, because cost depends on the systems, the data volume, the error handling required and whether a sandbox exists. Ongoing monitoring is a monthly managed service.